1. Field of the Invention
The present invention relates to a wire-cut, electric-discharge machining power source, and more particularly to a wire-cut, electric-discharge machining power source with which it is possible to perform electric-discharge machining operations at as high a speed as possible from roughing to finishing through utilization of a plurality of capacitors of different capacitances.
2. Description of the Prior Art
Wire-cut, electric-discharge machines are capable of highly accurate machining of a metal molds or the like having complicated configurations through the use of wire electrodes for electric-discharge machining. An example of a power source which has hitherto been employed with such discharge machine is shown in FIG. 1, in which the power source is formed by a transistor-capacitor discharge circuit comprising a power source V.sub.1, a charging resistor R, a transistor Tr for control use and a capacitor C.sub.0 connected between a wire electrode WIR and a workpiece WK. With such a power source, high-speed cutting of the workpiece WK can be performed by making the capacitance of the capacitor C.sub.0 large, the inductance of the discharge circuit small and the voltage of the power source V.sub.1 low. In this case, however, the roughness of the machined surface of the workpiece WK is increased by the increased capacitance of the capacitor C.sub.0. To avoid this, it is general practice in the prior art to imporve the surface roughness by decreasing the capacitance of the capacitor C.sub.0 in the case where a high degree of accuracy is required of the machined surface. But the conventional circuit arrangement of FIG. 1 has the defect that decreasing the capacitance of the capacitor C.sub.0 may sometimes result in unstable discharge and extremely lowered cutting speed.